Kimi Raikkonen has admitted he has had "small talks" with Red Bull about replacing Mark Webber next year.
Earlier reluctant to discuss his future beyond saying his Lotus contract is expiring, the 2007 world champion is now admitting that moving to the reigning world champion team is a real option.
Sebastian Vettel has made clear he would like to share the 2014 garage with his Finnish friend.
Raikkonen admitted: "It would be interesting to drive against him in the same car.
"It would be a big challenge, but that is why we are here. If you have a chance to be there you should take it.
"I would say Lotus or them (Red Bull) is the only options," the 33-year-old told British broadcaster Sky.
A key to a Raikkonen-Red Bull marriage would be to emulate his situation at Lotus, where the introverted Finn does minimal sponsor appearances.
"They might sound like stupid, small things but I've been long enough in the business to know what I want," he admitted.
It is thought that, Raikkonen aside, the only other candidates Red Bull would seriously consider are Daniel Ricciardo and Jean-Eric Vergne, who currently drive for the energy drink company's junior team, Toro Rosso.
But Australian Ricciardo admitted his cause has not been helped by a competitive dip in recent races.
"I haven't really come off a strong few (races) to give me bragging rights to say 'That's mine, everyone'," he smiled, according to Reuters.
Ricciardo said Red Bull continues to back young drivers with the ultimate aim that they emulate Vettel's feat and graduate to the top team.
But Toro Rosso boss Franz Tost said the prerequisite is title-winning potential.
"Both drivers would have to show an extraordinarily good second half of the season," he told Speed Week, "because, and we must never forget, we are talking about the champion team."
Vettel is making no secret that he is pushing hard in Raikkonen's favour, but on the other hand he is also not rubbishing Ricciardo or Vergne's chances.
"I don't think it's fair to compare Kimi with Daniel or Jean-Eric. Their careers are totally different," he is quoted by Brazil's Totalrace.
Ultimately, however, the triple world champion will have a say.
"It's not my decision, but if I am asked, I will speak my mind," said the German.
Dr Helmut Marko told Bild newspaper: "This is a team, and so we need to ensure the greatest possible harmony.
"The best decision is one that is made in agreement on all sides. This includes Sebastian."